1. Field of the Invention
The present invention relates to a press punching technique and, more particularly, to a press punching method and apparatus suitable for manufacturing a substrate of a semiconductor device.
2. Description of the Related Art
In recent years, there is a demand for high density mounting of semiconductor devices. In order to satisfy such a demand, BGA/LGA (ball grid array package/land grid array package) or CSP (chip size package or chip scale package) is used as a package of a semiconductor device. In the BGA and CSP, electrodes for providing external connection terminals can be arranged in even a semiconductor mounting area, thereby reducing a mounting area of a semiconductor chip such as an IC chip to the size of the semiconductor chip.
In the BGA or CSP, a semiconductor chip is mounted on a wiring board, and external connection terminals are provided on an opposite surface of the wiring board. In such a structure, generally, a small through hole is formed in the wiring board at a position where a land is formed on which each external connection terminal is provided. Accordingly, many through holes are formed in the wiring board in the same arrangement as that of the lands.
FIG. 1 is a plan view of a substrate (wiring board) of a BGA type semiconductor device. The BGA wiring board shown in FIG. 1 is formed by applying copper foil to a tape-like substrate material 2 and patterning the copper foil by etching. The tape-like substrate material 2 is previously provided with guide holes 4 so that the guide holes 4 are used for positioning the substrate material 2. Generally, the BGA wiring board has a multi-layered structure, and electrical connection between the layers in a perpendicular direction is achieved by using the through holes formed in each layer. Additionally, many wirings and lands 6 are formed in the wiring board 2, and the above-mentioned through hole is previously formed under each land 6. Accordingly, the through holes must be provided in the same arrangement as that of the lands 6.
FIG. 2 is a plan view of a substrate (wiring board) of a CSP type semiconductor device. The CSP wiring board shown in FIG. 2 is generally referred to as an interposer, and is formed in the same manner as that of the BGA wiring board. The tape-like substrate material 2 is previously provided with sprocket holes 8 so that the sprocket holes 8 are used for positioning the substrate material 2. Additionally, many wirings and lands 6 are formed in the wiring board 2, and the above-mentioned through hole is previously formed under each land 6. Accordingly, the through holes must be provided in the same arrangement as that of the lands 6.
The above-mentioned through holes can be formed by drilling by a small diameter drill, laser machining or press punching. The press punching is generally used since the machining cost of the press punching is lower than that of the drilling or laser machining.
When the drilling or laser machining is used, it is difficult to make many holes at the same time. Accordingly, the through holes are formed on an individual hole basis. On the other hand, the press punching can form many through holes by a single press stroke by arranging many punches in the same arrangement as that of the through holes to be formed. Accordingly, the press machining has a short machining time, and, thus, there is an advantage that a low machining cost can be achieved.
In recent years, the number of kinds of semiconductor devices is increased, and, thus, a service time of one kind of semiconductor device has been shortened. This means that a usable time of punches and dies, which are fabricated in accordance with the electrode arrangement of one kind of semiconductor device, is shortened. In such circumstances, if the punch and die for press punching are produced based on an electrode arrangement of a single kind of semiconductor device, a ratio of the cost of producing the punch and die to the manufacturing cost of the semiconductor device is increased. Thereby, there is a problem in that the manufacturing cost of each semiconductor device is increased.
If a single punch is used for making many holes on an individual hole basis by moving the punch, the positions of the holes can be changed by changing the movement of the wiring board according to numerical control (NC). However, this rendered the machining time to be as long as the drilling or laser machining. Accordingly, the advantage that many holes can be made at the same time is lost.